diff --git a/vcs.mk b/vcs.mk
index ef5761df..a282aa44 100644
--- a/vcs.mk
+++ b/vcs.mk
@@ -14,8 +14,7 @@ RESET_DELAY ?= 777.7
 #----------------------------------------------------------------------------------------
 # gcc configuration/optimization
 #----------------------------------------------------------------------------------------
-# -flto slows down compilation on small-memory and breaks on firesim-manager
-CXX_OPT_FLAGS := -O3 -fbranch-probabilities -march=native
+CXX_OPT_FLAGS := -O3
 
 VCS_CXXFLAGS = \
 	$(CXXFLAGS) \